It may be desirable to communicate rotation between a first shaft and a second shaft extending away from one another at an angle. The first shaft can be a driving shaft and the second shaft can be a driven shaft. The shafts can be connected to one another with a single universal joint, an arrangement known as a Hooke joint. However, the driven shaft may not rotate at a uniform angular velocity. In particular, during revolution the driven shaft may experience angular acceleration and deceleration in response to relatively constant angular velocity of the driving shaft.
A cardan joint engages two shafts with respect to another with an intermediate, revolving coupling member. First and second universal joints connect the first and second shafts, respectively, to the intermediate coupling member. The cardan joint arrangement imparts constant velocity to the driven shaft. The cardan joint can include a centering plate positioned in the intermediate coupling member that engages both shaft ends to generally maintain the same output angle of the driven shaft as the input angle of the driving shaft with respect to the coupling member. The centering plate can define an aperture for receiving rounded ends of the shafts. Alternatively, the centering plate can define rounded projections receivable in an aperture defined by the shafts.
Use of cardan joints in high joint angle applications may require more space, which may increase size, cost, and friction. Accordingly, it is desirable to provide a simple double joint that can operate at high joint angles.